Fast and Accurate Mass Flow Controller

Abstract

The invention relates to a mass flow controller designed for precise and rapid fluid flow management without using a proportional valve and a proportional-integral-derivative (PID) control loop. It features a solenoid control valve and a controller that uses a calibration database, potentially including a lookup table or neural network, to determine the appropriate solenoid coil current for various fluids, ensuring high-speed and accurate flow control.

1 . A mass flow controller, comprising:
 a fluid conducting channel without a proportional pump;   an inlet structured to receive a fluid;   an outlet structured to discharge the fluid via the fluid conducting channel;   a solenoid control valve that includes a spring, a plunger, an orifice within the fluid conducting channel, and a solenoid coil, where the solenoid coil current determines the position of the plunger to control the fluid flow rate; and   a controller configured to regulate the operations of the mass flow controller by determining the solenoid coil current without using a proportional-integral-derivative (PID) control loop. The solenoid current is determined based on a desired fluid flow rate derived from a process recipe and a calibration database stored in the controller, where the calibration database is created through a calibration procedure involving an external flow calibration apparatus connected to the outlet.   
     
     
         2 . The mass flow controller of  claim 1 , wherein the calibration database includes a lookup table. 
     
     
         3 . The mass flow controller of  claim 2 , wherein the lookup table contains calibration data for various fluids assessed at different temperatures. 
     
     
         4 . The mass flow controller of  claim 1 , wherein the calibration database is processed by a neural network. 
     
     
         5 . The mass flow controller of  claim 4 , wherein the neural network is trained using data obtained with the assistance of the external flow calibration apparatus. 
     
     
         6 . The mass flow controller of  claim 4 , wherein the neural network performs inference operations to determine the appropriate current for the solenoid coil after the controller receives a flow rate from a process recipe. 
     
     
         7 . The mass flow controller of  claim 1 , wherein, in the absence of current to the solenoid coil, the plunger blocks the orifice. 
     
     
         8 . The mass flow controller of  claim 1 , wherein the plunger blocks the orifice when a specified current is applied to the solenoid coil. 
     
     
         9 . The mass flow controller of  claim 1 , further comprising a flow sensor located downstream of the solenoid control valve. 
     
     
         10 . The mass flow controller of  claim 1 , wherein the calibration procedure can be conducted by a mass flow controller manufacturer, a semiconductor equipment vendor, or a semiconductor Fab operator. 
     
     
         11 . A method of controlling the flow rate of a fluid, comprising the steps of:
 creating a calibration database by connecting an external flow calibration apparatus to a mass flow controller;   including in the database a relationship between a flow rate and a solenoid coil current for various gases, vapors, and liquids;   storing the calibration database in a storage unit of the mass flow controller;   using a controller to determine the appropriate current to be directed to the solenoid coil based on a desired flow rate of a chosen fluid outlined in a process recipe and referencing the calibration database;   delivering the determined current to the solenoid coil to adjust the plunger of the solenoid control valve to a specific position; and   conducting a fluid from the inlet to the outlet of the mass flow controller without diverting any part of the fluid for flow rate measurement.   
     
     
         12 . The method of  claim 11 , further comprising creating a lookup table using data from the calibration database. 
     
     
         13 . The method of  claim 12 , further comprising determining the solenoid current based on data in the lookup table. 
     
     
         14 . The method of  claim 11 , further comprising developing a neural network using the calibration database and training the neural network with data from the calibration database. 
     
     
         15 . The method of  claim 14 , further comprising determining the solenoid current using inference operations performed by the trained neural network. 
     
     
         16 . A fluid delivery system, comprising:
 a mass flow controller equipped with a solenoid control valve, which includes a solenoid coil and a plunger, where the plunger's position relative to an orifice is determined by a solenoid coil current stipulated from a controller, thereby adjusting the fluid's flow rate;   an external flow calibration apparatus designed to be attached to the outlet of the fluid conducting channel within the mass flow controller, where the fluid conducting channel does not use a proportional valve for diverting any part of the fluid for flow rate measurement; and   a mechanism for determining the solenoid current corresponding to the fluid's flow rate, based on a calibration database created using the external flow calibration apparatus.   
     
     
         17 . The system of  claim 16 , further comprising a step for calculating the solenoid current by referencing a lookup table. 
     
     
         18 . The system of  claim 16 , further comprising a step for determining the solenoid current using a neural network. 
     
     
         19 . The system of  claim 16 , wherein the external flow calibration apparatus includes a flow sensor for evaluating the fluid dispensed from the outlet of the mass flow controller. 
     
     
         20 . The system of  claim 16 , wherein the external flow calibration apparatus includes a test procedure for generating various gases and liquids to calibrate the mass flow controller.